The present invention relates to a scribing method for forming a scribe line on a surface of a work (workpiece) made of a hard brittle material such as plate glass, ceramics plate or like.
In an known art, the Japanese Patent Laid-open Publication No. HEI 9-25134 discloses an apparatus for forming a scribe line on the work surface while applying vibrations to a work (workpiece) formed of a hard brittle material such as plate glass or ceramics plate. In such scribing apparatus, an outer cylinder of an air-cylinder assembly is fixed to a support member and an inner cylinder thereof is connected to one end of a vibration generation member. The vibration generation member has another one end to which a cutter holder is connected, and the cutter holder, to which a cutter is secured, is mounted to the support member to be slidable through a slide mechanism. When the cutter holder is urged by the air-cylinder assembly, the cutter held by the cutter holder is pressed against a surface of the work, and then, a high frequency voltage is applied to the vibration generation member to thereby expand or contract. According to the expansion/contraction motion (retractable motion) of the vibration generation member, the cutter is vibrated, and under this state, the support member is moved along the work surface to thereby form the scribe line on the work surface.
Incidentally, in a scribing method performed by using the scribing apparatus mentioned above, the cutter is pressed against the work surface every time of respective vibration periods of the cutter, and according to such pressing force, the work surface is plastically deformed and fine recesses are hence formed thereon. Cracks will be formed from such recesses in a work thickness direction. When the recesses are formed to be continuous, the cracks are also formed to be continuous, thereby forming a scribe line.
However, in a prior art, analysis or research of a shape or size of the tip portion of the cutter has not sufficiently been made, and a cutter having merely a sharp tip end portion has been utilized. For this reason, the cracks are formed so as to extend from the recesses not only in a direction of a scribe line but also in a direction crossing the scribe line, and therefore, vibration energy could not concentrically utilized for effectively forming the cracks along the scribe line. That is, the effective deep cracks along the scribe line could not be formed, and accordingly, it is impossible to satisfy the requirement of easily breaking the work along the scribe line.
An object of the present invention is to substantially eliminate defects or drawbacks encountered in the prior art mentioned above and to provide a scribing method for forming a scribe line on a surface of a hard brittle work (workpiece) capable of forming effective cracks along a scribe line and easily breaking the work along the scribe line.
This and other objects can be achieved according to the present invention by providing a scribing method of forming a scribe line on a work surface comprising the steps of preparing a scribing apparatus provided with a scribe body including an abutment member having at least first and second ridgelines and a sharp tip end portion and a vibration generating member for periodically applying vibrations to the abutment member, applying a vibration to the abutment member to vibrate the abutment member with the tip end portion thereof abutting against the work surface and relatively moving the scribe body along the work surface to thereby form a scribe line on the work surface,
wherein a first angle constituted by the first ridgeline of the abutment member and the work surface and a second angle constituted by the second ridgeline thereof and the work surface are different from each other and the first and second ridgelines are opposed in the moving direction of the scribe body.
In preferred embodiments, the first angle is made larger than the second angle, and the second ridgeline is directed to the relatively moving direction of the scribe body and the first ridgeline is directed to a direction opposed to the moving direction of the second ridgeline.
The abutment member is pressed against the work surface by the periodical vibrations of the vibration generation member so as to form a plurality of plastically deformed portions to the work surface by the abutment member which is pressed against the work surface with a space from each other and cracks are formed from the plastically deformed portions at portions corresponding to the first and second ridgelines so as to extend in the moving direction of the scribe body, the cracks being connected to each other to thereby form a scribe line. In this example, when a moving speed of the scribe body is denoted as V(mm/sec) and a vibration frequency is denoted as F(number/sec), a feed amount S of the abutment member per one period of vibration is expressed by an equation of:
xe2x80x83S(xcexcm)=(V/F)xc3x971000.
When a length of the deformed portion in the moving direction is denoted as L(xcexcm), a total length of the cracks is denoted as xcex94L, a feed amount S of the abutment member is expressed by L less than Sxe2x89xa6L+xcex94L, in which the lengths L and xcex94L are determined by a pressing force of the abutment member, a vibration load and a shape of the abutment member.
In an embodiment in which the first and second ridgelines have equal angles to each other with respect to a central axis of the tip end portion of the abutment member, and the first and second angles of the first and second ridgelines to the work surface may be made different by inclining the central axis of the tip end portion towards the moving direction of the scribe body. The first and second angles have a difference in angles in a range of 1xc2x0 to 10xc2x0.
According to the preferred embodiment of the present invention mentioned above, deep cracks can be formed along a line to be scribed by opposing the first and second ridgelines of the abutment member such as diamond penetrator having angles different from each other with respect to the work surface and by making coincident the extending direction of the cracks with the feed (moving) direction of the scribe body.
Furthermore, the cracks can be formed more precisely along the feed direction and can be more fine, by making the first angle constituted by the first ridgeline larger than the second angle constituted by the second ridgeline, and by making the second ridgeline to be directed to the moving direction and the first ridgeline to be directed to a direction opposed to the moving direction.
The scribe line can be more precisely formed by connecting the cracks extending from the respective plastically deformed portions, i.e. recesses, formed to the work surface with space in the feed direction.
Furthermore, there is usable an abutment member having tip end portions which are easily manufactured.
Furthermore, the cracks stably extend by making the first and second angles to have a difference in angles in a range of 1xc2x0 to 10xc2x0.
The nature and further characteristic features of the present invention will be made further clear from the following descriptions made with reference to the accompanying drawings.